The present invention relates to security tags and, more particularly, to deactivatable security tags for use with electronic article surveillance systems for the detection of unauthorized removal of articles from secured spaces.
Electronic article surveillance (EAS) systems for detecting and preventing theft or unauthorized removal of articles or goods from retail establishments and/or other facilities, such as libraries, are well known and widely used. In general, such security systems employ a label or security tag which is affixed to, associated with, or otherwise secured to an article or item to be protected or its packaging. Security tags may take on many different sizes, shapes, and forms, depending on the particular type of security system in use, the type and size of the article, etc. In general, such security systems detect the presence of an active security tag as the security tag (and thus the protected article) passes through a surveillance zone or passes by or near a security checkpoint.
Certain prior art security tags work primarily with radio frequency (RF) electromagnetic field disturbance sensing electronic security systems, such as, but not limited to those disclosed in U.S. Pat. No. 3,810,147 entitled "Electronic Security System", U.S. Pat. No. 3,863,244 entitled "Electronic Security System Having Improved Noise Discrimination", and U.S. Pat. No. 5,276,431 entitled "Security Tag For Use With Article Having Inherent Capacitance", and their commercially available implementations and counterparts. Such electronic security systems generally establish a radio frequency (RF) electromagnetic field in a surveillance zone through which articles must pass when being removed from the controlled premises. A tag having a resonant circuit is attached to each article, and the presence of the resonant circuit in the surveillance zone is sensed by a receiving system to denote the unauthorized removal of an article.
Articles which are authorized for removal from the controlled premises require the attached security tag to be deactivated prior to removal. Physical deactivation of a tag having a resonant circuit may be performed by: (1) altering the tag to detune or disable the resonant circuit, (2) shielding the resonant circuit from the incident RF energy or (3) removing the tag from the article. All of these physical deactivation techniques require the security tag be identifiable and accessible, which prohibits the use of tags embedded within merchandise at undisclosed locations or tags concealed in or upon the packaging.
The trend in the electronic article surveillance industry is to install a tag in a product at the time the product is being manufactured, since at this stage, it is relatively inexpensive to install the tag and also because the tag may be concealed or hidden from view thereby discouraging fraud. Embedding the tag in the product or the product packaging requires that the tag be remotely deactivatable.
Remote tag deactivation may be achieved by electromagnetic means. Such tags can be conveniently deactivated at a checkout counter or other such location by being momentarily placed above or near a deactivation device which subjects the tag to RF energy at a power level sufficient to cause one or more components of the security tag's resonant circuit to either short circuit or open, depending upon the detailed structure of the tag. Typical methods for causing an open or short circuit employ dielectric breakdown and fusible links. All such techniques require a predetermined RF energy level from specialized equipment to properly deactivate the tags.
There are circumstances where tags may be installed in articles, and the articles put into legitimate use without the tag first being deactivated. There is a need to permanently deactivate such tags during use without benefit of specialized equipment in order to minimize the likelihood that the tag will later create a false alarm if the article should later pass through an article surveillance system.